Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Because compression of the air may cause an increase in air temperature, a charge air cooler may be utilized to cool the heated air, thereby increasing its density and further increasing the potential power of the engine. To maintain the charge air cooler at a desired temperature, and to provide a desired level of cooling to the heated air, ambient air may be directed over the charge air cooler via grille shutters positioned at the front of the vehicle. Further, to reduce the accumulation of condensate in the charge air cooler, which may occur when internal surfaces of the charge air cooler are cooler than the dew point of the compressed air, the charge air cooler may include a valve configured to selectively modulate the volume of the charge air cooler, thus increasing the intake flow velocity through the charge air cooler to remove and/or reduce accumulated condensate. If degradation to either the grille shutters or the variable volume valve occurs, the cooling capacity of the charge air cooler may be reduced, leading to overheating of the engine and associated components under some conditions. Further, due to increased air pressure that may result when the variable volume valve is degraded, the turbocharger may degrade.
The inventors herein have recognized the issues with the above approach and offer a method to at least partly address them. In one embodiment, a method comprises adjusting an operating parameter in response to a degraded grille shutter, the degraded grille shutter determined based on a temperature difference across a charge air cooler.
In one example, degradation of the grille shutters may be determined based a temperature difference across the charge air cooler during steady state operating conditions. For example, the difference between the temperature upstream of the charge air cooler and the temperature downstream of the charge air cooler may be determined and compared to an expected temperature difference for the known conditions. If the measured temperature difference is different that the expected temperature difference, degradation of the grille shutters may be indicated, and various engine operating parameters may be adjusted to reduce engine overheating.
In another example, degradation of the variable volume charge air cooler valve may be determined based on a pressure difference. For example, the pressure downstream of the charge air cooler may be compared to an expected pressure at a given throttle angle and wastegate position (e.g., level of boost), and if the measured pressure is different than expected, degradation may be indicated.
In this way, degradation of charge air cooler components may be identified without the use of additional sensors. By identifying degradation in components that effect charge air cooler temperature and adjusting operating parameters to account for the degradation, overheating of the engine and/or associated components may be reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.